Onions produce the chemical irritant known as syn-propanethial-S-oxide; this stimulates the eyes' ______ glands which release tears.

lachrymal

The correct answer is Option (1) → lachrymal

Onions produce the chemical irritant known as syn-Propanethial-S-oxide. It stimulates the eyes' lachrymal glands so they release tears. Scientists used to blame the enzyme allinase for the instability of substances in a cut onion.